There are plasma sterilization apparatuses as background arts which are disclosed in Japanese Laid-Open Patent Publication (KOKAI) No. H10-099415A (first background art) and Japanese Laid-Open Patent Publication (KOKAI) No. H07-018461A (second background art), and these background arts are shown in FIGS. 5 and 6 in schematic structural cross-sectional views, respectively.
In FIG. 5, this first background art plasma sterilization apparatus includes: a first chamber 114 having a plasma generation unit 112 in which plasmas are generated under an atmospheric pressure; a second chamber 118 featuring a pressure-resistance structure, in which subjects 136 to be treated can be placed; and joint pipes 124 which connect the first and second chambers 114 and 118 to each other in openable and closable manners, and each of which has an on-off valve 120 for controlling a flow of gas, containing sterilization factors, fed from the first chamber 114 to the second chamber 118, and a compressor 122 formed as a pressurized unit. A pressure regulating unit 116 is connected to the second chamber 118 so as to maintain a pressure in an interior of the second chamber 118 constant by feeding the gas thereto and exhausting the gas therefrom. In the plasma generation unit 112, at least one part of a mixture of gas and liquid can be ionized by using a pulse power source, and the ionized mixture thus obtained forms the sterilization factors.
Like this, in addition to the second chamber 118 for sterilizing the subjects 136 to be treated, there is the first chamber 114 for storing the sterilization factors, and both the first and second chambers are connected to each other by the joint pipes 124 having the on-off valves 120, whereby it is possible to carry out not only the storage of the sterilization factors necessary for the sterilization but also a pretreatment of the subjects to be treated, such as a drying treatment and so on, and whereby it is possible to efficiently carry out an effective sterilization treatment in that the subjects to be treated can be contacted with a large amount of the sterilization factor in a short time.
Also, in FIG. 6, according to the second background art plasma sterilization apparatus, a lid 202 is opened, and a vessel 218 to be sterilized is put into a vacuum container 201. Then, the lid 202 is closed, and the vacuum container 201 is exhausted by a vacuum pump 204 until a sufficiently lower pressure is obtained than a pressure at which a plasma is generated in the vacuum container. Subsequently, a gas is introduced from a gas source 214 into the vacuum container at a suitable flow rate, and a valve 215 is regulated so that the pressure suiting the plasma is maintained. On the other hand, the vacuum pump 204 is continuously operated so that the pressure is stabilized, and thereafter a high frequency power is applied from a high frequency power source 212 to an electrode 208 to thereby generate the plasma in the vessel 218. After the plasma is maintained over a time during which the sterilization is sufficiently carried out, the application of the high frequency power is stopped, resulting in a completion of the sterilization of the vessel 218. Also, when the application of the high frequency power is stopped, the introduction of the gas is simultaneously stopped, and the operation of the vacuum pump is stopped after the exhaust is momentarily continued. Then, an atmosphere introduction valve 217 is opened to thereby introduce an atmosphere into the vacuum container. Thereafter, the lid 202 is opened, and the vessel 218 is took out.    Patent Document 1: Japanese Laid-Open Patent Publication (KOKAI) No. H10-099415    Patent Document 2: Japanese Patent Publication No. 3209944